Author: Gray, 1851
Diagnostic Features:
Head without laterally expanded blades; eyes horizontally oval, with lengths less than 2 times height; nictitating eyelids internal; spiracles present and very small; anterior nasal flaps formed into slender barbels; internarial width about 2.5 to 3.2 times the nostril width; labial furrows very long; teeth small, with acute narrow cusps, lateral cusplets, and strong basal ledges and grooves, not bladelike and similar in both jaws; posterior teeth not comblike; tooth rows 49 to 60/43 to 54. Precaudal pits absent. First dorsal fin small and not keel-like, much shorter than caudal fin; first dorsal base well ahead of pelvic bases, slightly closer to pectoral bases than pelvics; pectoral fins with radials confined to bases of fins; ventral caudal lobe absent or very weak; no undulations or ripples in dorsal caudal margin. Neurocranium without supraorbital crests; vertebral centra with strong, wedge-shaped intermedial calcificiations. Valvular intestine with a spiral valve of 14 to 16 turns. Colour grey above, light below, no colour pattern. Development viviparous, with a unique globular placenta.
Remarks:
The single genus and species, Leptocharias smithii, is conventionally placed in the family Triakidae or Carcharhinidae, but a study of its morphology (Compagno, 1979) shows that it is rather divergent in morphology from triakids. It is thereby placed in its own family, Leptochariidae. See Compagno (1979) for a detailed discussion of the morphology and relationships of Leptocharias.